Alternating-current rheostat for polyphase circuits.



W. H. GAULKE.

ALTERNATING CURRENT RHEOSTAT FOR POLYPHASE CIRCUITS.

APPLICATION FILED JAMS. 1911. 1,051,098.

Patented Jan. 21, 1913.

2 SHEET S-SHEET 2.

UNITED STATES PATENT OFFICE. wILnIAm H. GAULKE, or MILWAUKEE, WISCONSIN, ASSIGNOR. To INDEPENDENT YELEQTBIC MANUFACTURING COMPANY, A conrom'rron or Wisconsin.

. p ALTERNATING-CURRENT RHEOSTAT FOR IPOLYPHASE CIRCUITS.

Specification of Letters Patent. Patented J an, 21, 1913, Application filed January 3, 1911. Serial No. 600,510. i I

To all whom it mag camera Be it known that I, WILLIAM H. GAULKE,

of Milwaukee, Wisconsin, have invented an Alternating-Current Rheostat for Polyphase Circuits, of which the following is a specification. y

This invention relates to rheostats for controlling polyphase-motors and is adapted for use with currents'of two, three or number of phases. p I

The object of my invention is to provide any a simple form ofrheostatpartlcularly adapted to control synchronous inductionmotors, though it is also adapted for use in other situations for controlling poly phase-circuits. Further, I aim to provide such a rheostat with an automatic no-voltage release, to wit, a device adapted, in the case of failure of the power, to return the rheostat immediately to the starting posi-- tion.

,- formof rheostat constructed according to my invention; Fig. 2 is a side-view of the front-portion thereof; Fig. 3 is a longitudinal section .therethrough, on the plane 3 of Fig. land on a larger scale; Fig. 4: is a front-view of another form of my improved rheostat with automatic no-voltage release; and Figs. 5 and.6 are distribution diagrams showing the connections of the rheostat for threeand two-phase circuits respectively.

The reference letters refer each to the same part in each figure of the drawings.

Referring to the first form, the frontplate of the rheostat, which is of slate or other insulating material, is designated a, being secured by screws 6 to the rheostat case, as usual. On this plate are mounted four posts a which carry two parallel bars d.

The parallel bars (Z serve as guides for the shiftable contact-bar e which operates to make contact between three series of contact k are disposed three independent eontactblocks m which press upon the respective contact-blocks f, g and h and are confined laterally by the longitudinal bars 2' and the blocks k and pins Z, but are adapted to shift vertlcally, to, take up wear andprovide a uniform and constant pressure upon the contact-plates. This pressure is provided by means of a-pair of yokes n, each pressmg upon two adjacent contact-blocks and held resiliently thereagainst by springs 0, which are mounted on central-posts .p on the blocks 75, said springs abutting against nuts 9 on the ends of said posts. By means of the springs and yokes, the pressure is uniformly distributed upon the three contact-blocks m. v

A shifting-handle r is conveniently secured to the contact-bar e by means of an angle 8, and to prevent the bar from binding against the guides 03 and hold it parallel, a third bar t is secured, in parallel relation with the guides d, to the contact-bar e, and slides in a guide-post u,which is preferably somewhat beyond the line of the posts 0.

The travel of the contact-bar is indicated by the fulland dotted-line positions in Figs. 1 and 2. Terminal-posts 'v are provided upon the plate. a for convenience in making the connections herein below .de-v scribed. l

In the second form of my rheostat, I-have illustrated a face-plate A secured to the rheostat-case by screws B and having mounted thereon four posts C carrying the parallel guide-bars D, upon which slides the contact-bar .E, which electrically connects the contact-pieces F, G and H, all substant-ially as described in th'ecase of the first form. In connection with this form, I provide means for automatically returning the bar E, when released, to the starting-point, which is its left-hand position in the drawing, said means comprising preferably. a barrel I, turning upon a centralpost J and connected therewith by a spiralspring K, which is adapted to turn the barrel in a counter-clockwise direction; and a tape or cord Lattached to said barrel connects it operatively with the bar E by means of an angle or bracket M, as shown.

At the right -hand side is mounted a pivot-post N, on which swings through a small angle a bar 0, this latter having secured to its end an armature P adapted to be attracted by an electro-magnet Q, shown partly in section. The magnet-core R and armature P are constructed according to the principles enumerated in my United States patent application No. 587 ,823, filed Oct. 19. 1910, the former being hollowed out as shown at 7-" and the latter of a slightly smaller diameter and in concentric position,

said latch-piecea surface 25 which catches over the roller and is nearly at right angles to the direction of movement of the contactbar. The angle which the surface t makes with the line of movement of the contact-bar is regulated by means of an adjusting-screw t which is screwed into the bar 0 and locked by anut t It will be seen that by increasing or' diminishing the effective length of the screw t the surface 22 is changed through a slight angle and thereby the resultant force created by the reaction of the spring K and acting upon the surface If to turn the bar 0 away from the magnet is increased or diminished. Owing to the presence of the roller u, the sensitivity of this arrangement is especially great, because the friction of release is almost entirely eliminated, thereby making the apparatus respond to the exact diminution of the magnet-strength to which it is set. When the magnet-strength has been fixed, the predetermined voltage permitting the release of the contact-bar can be exactly adjusted by means of the screw t as Well as by the abutshown diagrammatically in Figs. 5 and 6,

the contact-pieces and contact-bar being shown in outline and connected by the reg and it or F, G and H are connected through three of the terminals 'v or V to the three terminals of a synchronous threephase armature, w, as in Fig. 5, or a twophase armature X, as shown in Fig. 6. As the contact-bar is moved from the startingend of its travel along the contact-pieces, it short-circuits successive sections of resistance by connecting any set of three of said contact-pieces, as will be clear without further explanation.

I wish it understood that my invention is not limited to the use of all the above described features and constructions, for some may be omitted and others may be varied or modified in various ways, as will readily occur to those skilled in the art.

Having thus described. my invention, what I claim as new.and desire to secure by Let-.

ters Patent is: 1

In a rheostat, the combination, of a plurality of parallel rows of contact-pieces, a contact-bar disposed across said rows so as to cover a piece in each row simultaneously, means for guiding said bar in a movement parallel to itself and to said rows, the contact-pieces in each row being united together by interposed resistances, a plurality of independent contact-blocks, one for each row and resting on one of the contactpieces thereof, each of said blocks being free to move in said contact-bar toward and yoke, and an abutment for said spring on the outer end of the post.

In witness whereof I have hereunto set my hand in the presence of two witnesses.

WM. H. GAULKE. Witnesses FRANK KRAEMER, Gnonon W. CoLLEs. 

